Polymerization of refinery unsaturates and preparation of improved motor fuels



Pnemed sepa 9, 1941 y roLyMEmzA'rioN oF REFINERY uusa'ru-` Barns ANDPREPARATION or nuPnovEn MOTOR FUELS Eldon E. Stahly, Baton Rouge, La.,assignor to Standard Oil Development Company, a corporation of DelawareApplication October 1, 1937, Serial No. 166,752

6 Claims.

The present invention resides in a method for producing gasolinehydrocarbons from normally gaseous hydrocarbons by acid'polymerizationof the latter. It is particularly directed to a process for convertingmixtures of Cs and C4 oleflns, with or without C5 olens, by the actionof sulfuric' acid of suitable strength into liquid motor fuel.

More particularly, it resides in a process in which normally gaseousmixed oleiins of said type are converted into liquid fuel in a singleoperation.

It has already been proposed to subject hydrocarbon fractions containingmixtures of isoand normal butylene with or withoutv other unsaturatedhydrocarbons to the 'action of sulfuric acid of a particularconcentration at a temperature between about 150 F. and 300 F. to formCs hydrocarbons composed of a mixture of di-isobutylene and copolymer ofnormal and isobutylene. This mixture, eitheras such or preferably afterhydrogenation, is a highly desirable constituent of a motor fuel.

A mixture of hydrocarbon polymers, mainly of branched chain structureranging from Cs to Cio hydrocarbons and isopropyl ether 'and/orisopropyl alcohol, can be obtained by the method described above if thehydrocarbon fraction subjected to the acid .treatment 1contains amixture of C3, C4, and Cs olefins. Such mixed polymens are preferablyobtained in a single operatiorf by subjecting a mixture of Ca, C4, andC5 olefins to the action of sulfuric acid of a concentration rangingfrom about 55% to about 80% at a temperature ranging from about 175 Fftoabout 300 F., and preferably under a pressure suilicient to maintain thenormally gaseous hy ,drocarbons inthe liquid state. When the feed stockis free from Cs hydrocarbons, the product will contain-hydrocarbonsranging from Ca to 012+. v

.The process may also be carried out inthe gaseous phase. Due to thefact that the degree of dispersion of these hydrocarbons when in thegaseousphase in sulfuric acid is not as complete' as when they are inthe liquid phase, it is preferablewhen carrying-out the reaction in theI 10 knocking characteristics.

(Cl. id-9) gaseous phase, to introduce the normallygaseous hydrocarbonsinto the reaction zonein the liquid state, the temperature in this'zonebeing so correlated to the pressure that the hydrocar- 5 bons, uponbeing dispersed in the sulfuric acid,

are converted to the gaseous phase. vThe hydrocarbon above describedmethods are suitable for use as motor fuels, and have very However,these polymers are unsaturated, and in many instances it is desirable tohydrogenate them in order to saturate the oleiln double bong; .before,their use in gasoline. It has been f und that this hy- 15 drogenationalso reduces the alcohols and ethers present to the correspondinghydrocarbons, thereby causing a loss in the anti-knockingcharacteristics of such oxygenated compounds. An

actual loss in yield of product suitable for use in 20 gasoline alsoresults, as isopropyl alcohol and ether are reduced to propane.

. It has now been found that. these losses can be prevented, andimproved yields of improved motor fuels may be obtained by carrying outthe .process of the present invention. In one speciflc embodiment of theprocess the isopropyl ether formed is separated from the olefin polymerproduced, the latter is hydrogenated wholly or in part, and theisopropyl ether is then reblended with the hydro-polymer and anyresidual olefin polymer. Other and further objects of this invention andillustrative embodiments thereof will be presented in the followingdescription and in the attached drawing.

-As previously stated, it is preferred, according to the presentinvention, to operate under a pressure such that the mixture of Cs, C4,and/or C5 hydrocarbons is maintained in the liquid state.

o At the preferred operating temperature of 200 to 225 F., a suitablepressure will be between 400 lbs/sq. in. and 600 lbs/sq. in. It isofcourse evident that the only upper limit on the pressure which may beemployed is that dictated by eccnomcal operation. Under these preferredoper-l poiymers obtained by. the.

pronounced anti-` between 55% and 757 they will vary vidual case.

ating conditions the acidstrength is preferably The effect of propyleneon the product is noticeable when the feed stock contains even as littleas mole per cent of propylene based on a total feed containing 48.5 moleper cent of olens. Generally a feed having a higher percentage ofpropylene. Preferably, it should be present in an amount at least equalto the amount of butylenes where these are the only olens in the feedstock. An increase in the ratio of propylene to normal butylene over oneto one favors the formation of isopropyl ether. In generaL, it vmay bestated that any feed stock which contains a substantial amount ofpropylene,together with C4 and/or C5 oleins, is suitable for the processof the present invention.

The feed stock most commonly employed for the process of the presentinvention is a refinery gas obtained from crude'distillation', cracking,destructive hydrogenation, or other thermal process. These gases maycontain as high as 50% of olens composed mainly of propylene, isoandnormal butylene with small amounts of the' amylenes. 'I'he remainder ofsuch refinery gases consists of C1 to C5 paraillns and hydrogen. Thecapacity of the polymerization chamber may be increased by isolating theoleinic constituents from the renery gas by any suitable method, such asby liquefaction of the-Cs to C5 constituents of such gases and theextraction of the olefins from said liquefied fraction by any commonselective solvent such as sulfur dioxide. Or, if desired, the C3 to C5hydrocarbons may be segregated from the lighter constituents.

When the only available feed stock is one mainly composed of C3 and C4paraillns with or without C5 it to the parailins to olens. Thisconversion may be either cracking or catalytic dehydrogenation,preferably the latter. A particularly suitable feed stock is oneobtained by the cracking or catalytic dehydrogenation of a mixture ofpropane and isobutane or a naturally occurring mixture of isoand normalbutane with propane. 'Ihe former, when thermally decomposed, produces anoleflnlc mixture mainly composed of propylene and isobutylene which,when subjected to the process of the present invention, yields a mixtureof olens of particularly highly branched nature, together with isopropylether. This mixture, especially when the oleilnic constituents thereofare hydrogenated, is an exceptionally good blending agent for motorfuels.

The reaction time best suited for the process of the present inventionmay be most readily understood when expressed in liters of liquidhydrocarbon feed perhour per foot of acid height in the polymerizationzone. This feed rate may vary between about 1%g liters per hour Perfootof acidheight and about I liters per Ahour per foot of acid heightwith an acid column having a cross sectional area of about 0.05 sq. ft.These specific values are only exemplary, since with acid columns ofdifferent cross-sectional area. -They are, however, -indicative of theorder offeed rate to be employed and can be readily ascertained for eachindi- The-liquid hydrocarbon feed may be introduced into the acid in thepolymerization zone` alundum thimble, or thru Jets which impart a itwill be desirable to employ paraflins, it ,is necessary to subject athermal treatment for the conversion of` thru a porous thimble, such asan of course, apparent that the size of the jet suit different totalfeed 'feed and product is discharged into a y which4 the acid settles tothe bottom isfactory results have been obtained with Jets havingopenings of 0.018" and 0.023". It is,

opening may be chosento rates.

After the separation of the normally liquid constituents from theproduct issuing from the polymerization zone, a residual gas mixture,which still contains a substantial percentage of C: to Cs olens. may beobtained. This residual gas mixture may be recycled to the fresh feed,

or may be sent thru a second polymerization unit y `of the same type.

When recycling is employed, saturated normally gaseous hydrocarbonsbuild up in the feed. For this reason, it is advantageousfrom time totime to divert therecycled stock to a cracking or catalyticdehydrogenation chamber wherein the saturates are converted tocorresponding olens. gas may be diverted to a thermal polymerizationunit for the'conversion of normally gaseous paramns intoI hydrocarbonsboiling within the'gasoline range. Whencatalytic dehydrogenation isemployed, the dehydrogenation chamber is maintained at a temperatureranging from about 950 to 1100 F. and under atmospheric or only slightlyelevated pressure. A suitable catalyst for this conversion is onecontaining, as itsessential catalytic constituent, an oxide or asulfide, or other compound, of a metal of group VI of the periodicsystem which is preferably associated with a carrier; such as bauxite,kaolin, alundum,` active carbon, etc., or with a diflicultlyreducibleoxide, such as alumina, thoria, silica, etc. When a thermalpolymerization unit is employed for processing the recycle gas, it ismaintained under a pressure of at least 500 lbs/Sq. in. and under latemperature' between about 900 F. and 1200 F., depending upon thecomposition of the recycle gas.

Ordinarily the acid in the polymerization zone passes therethruconcurrent with the hydrocarbon feed and the mixture of acid,unconverted separator in from which it is drawn off and returned to thereaction chamber. During the process a content of alkyl lhighdegree ofdispersion to the liquid feed. Sat- 7 5 sulfates, mainly isopropylsulfate, is built up in the acid. Up to acertain extent the presence ofthese sulfates in the acid exerts a beneficial effect upon theequilibrium of the polymerization process. For this reason it may bedesirable to add alkyl sulfates to the fresh feed.

. Should the content o f alkyl sulfates in the circulating acid becomeso high that removal of some or all of these sulfates is desirable, thismay be done by arranging in the acid return line a reaction chambermaintained under conditions suitable for the decomposition of thesealkyl sulfates. This chamber may be so operated, namely, at atemperature somewhat 'above the temperature employed in the mainreaction zone, as

to convert the alkyl sulfates into ethers containing smaliamounts ofalcohols. Alternatively a hydrolyzing agent, such as water or an alkali,may be fed into this chamber and the conditions so adjusted in a knownmanner as to convert the balkyl sulfates into the corresponding alcoholscontaining small amounts of ether. When this latter method is employed,it is usually necessary to adjust the concentration of the acid beforereintroducingv it into the polymerization zone. 4If caustic soda is usedas the hydrolyzingagent. it

unnecessary to take measures to remove the resulting sodium acid sulfateor sodium sulfate Alternatively, the recycle from the circulating acid,since the presence of either of these salts is not detrimental tothepolymerizing action of the sulfuric acid.

As previously stated, itis preferable to hydrogenate at least part ofthe normally liquid oleiinic hydrocarbons obtained as a result of theacid treatment. If these liquid products are free from sulfur,'thehydrogenation is preferably` carried out in the presence of a highlyactive nickel catalyst, that is a nickel catalyst prepared by theroasting and reduction with hydrogen of a freshly precipitated nickelcompound. The nickel so prepared is used to best advantage when disposedon a carrier, such as kaolin, pumice, etc. When such a catalyst isemployed, the hydrogenation is generally carried out at a pressure of atleast 50 lbs/sq. in. and at a temperature between abouty300 and 600 F.

Should the normally liquid hydrocarbon prod- .uct contain sulfur, it isadvisable to employ la hydrogenating catalyst which is immune topoisoning by sulfur. The preferred catalysts of this type are thosewhich have previously been menqtioned -for use in the dehydrogenationof' normally gaseous hydrocarbons. When a catalyst of thisvtype isemployed, ed for the hydrogenation is generally somewhat higher thanthat required for hydrogenation in the presence of a nickel catalyst.

If it is .desired to employ a. nickel catalyst for the hydrogenationoperation, measures may be taken to preclude the presence of sulfur inthe liquid hydrocarbon feed to the hydrogenation chamber. This is bestaccomplished Aby scrubbing the normally gaseous hydrocarbons employed asa feed stock to the polymerization chamber with caustic. The e 'nationof sulfur from this feed stock also improves the polymerization stage ofthe process. Sulfur may often be removed from the normally liquidproducts by vsuitable fractionation. these products may also be reducedto the necessary extent by caustic washing or by treatment of theseproducts in the vapor phase with a desulfurizing agent, such as bauxite,ferrous sulfide, fullers earth, alumina and the like.

While in the preferred embodiment of the present invention the isopropylether is separated from the normally liquid product before the latter issubjected to hydrogenation, this step may be modied. The separatedisopropyl ether will always contain a considerable amount of hexylenewhich is formed in the polymerization chamber and which may be improvedas a motor fuel constituent by hydrogenation. The complete separation ofthese two compounds by fractionation is practically impossible, and itmay accordingly be desirable in producing a fuel to remove, prior to thehydrogenation, only so much of the isopropyl ether as can be separatedsubstantially free of hexylene.

This separation of the isopropyl ether from the hydrocarbon polymers mayalso of course be carried out in any other suitable manner, such-as bytreatment of the reaction product with solvents having a selectivesolvent action between the ether and the hydrocarbons, such as aqueousalcohol.

The products of the process of the present invention, having a highlybranched structure and having a boiling range nearly commensurate withthat of gasoline, canbe readily converted into a gasoline of high octanenumber by the addition of the necessary amount of low boiling hydrothetemperature best suitl highly .saturated motor` vention is graphicallycarbons to properly adjust their vapor pressure, 75

, the liquid state through line I3 which is below C1 hydrocarbons andthe addition, if necessary, of certain high boiling compounds to providea gasoline of the necessary end point. As suitable additions of lowboiling point may be mentioned iSO-pentane and butane or iso-butane.When it is necessary to add high boiling hydrocarbons this may be donewith a simultaneous improvement in the octane number of the `total blendby the addition of aromatic extracts of heavy naphthas, that portion othe extract which has an end boiling point of about 400 F. beingselected. In many instances, however, the product of the process of thepresent invention has a suiiiciently high end point to make the additionof extraneous heavy hydrocarbons unnecessary.

The nature o the process of the present inillustrated in theaccompanying drawing in which the single gure is a front elevation indiagrammatic form of an apparatus suitable for carrying out saidprocess.

Referring to the drawing in detail, I is a feed line for theintroduction of Cs to C5 hydrocarbons into the unit; Arranged in lli e Iis a compressor 2 `by which the C3 and C5 hydrocarbons are liquefied andpumped thru the system. The liquefied feed stock is fed intopolymerization chamber 3 through a porous thirnble 4. Sulfuric acid ofsuitable strength is fed into chamber 3 at its bottom through line '.i.V

The mixture of sulfuric acid,` unconverted feed and reaction productleaves reaction chamber Y3 through line 6, passes through cooler 1 intoa settling chamber 8 provided with an interface indicator 9. Thesulfuric acid settles to the bottorn and is drawn offl through line 5,which returns it to the reaction chamber 3. The mixture of normallyliquid reaction product and liqueiied normally gaseous unconverted feedleaves separator 3 through line I0, which discharges it into still Ilwhich is maintained under such conditions that' unconverted feed,isopropyl ether, and any' hexylene formed, leavesthe top thereof invapor form through line I2, and hydrocarbons having seven or more carbonatoms leave the bottom in provided with a valve III and a branched lineI5 in which the flow of liquid is controlled by valve I6. With valve I6closed and valve I4 open, the liquid reaction product is conducted byline I3 to storage tank I1. By suitably controlling valves I4 and I6,part'or all of the liquid product may be conducted by line I5 throughheating coil I8 i'nto hydrogenation chamber I9.

Line I5 is provided with a branch 20 through which the necessaryhydrogen forfthe hydrogenation of the liquid product is introduced intothe hydrogenation chamber.- The product from the lrvdrogenation chamberpasses into separator 2I from which the hydrogenated hydrocarbons aredrawn olf at the bottom through line 22 by which they are fed to storagetank 23. Excess hydrogen leaves separator 2| through line 24 and may berecycled to the hydrogenation chamber.

The unconverted feed and the products boiling are conducted by line I2to a. partial condenser higher boiling constituents thereof areliquefied and returned to the top of still II as reflux condensate byline ture leaves condenser 25 through line 21 by which it is fed tocooling coil 28 after the pressure thereon has been suliicientlyreleased by pressure release valve 29'in vline 21. The mixture is thendischarged into a separating chamber 30 provided with a liquid levelindicator.

25 in which part of the- 26. vThe remainder of the mixisopropyl forhydrolysis, leaves vessel I point just ahead of .this valve, with abranch a reaction chamber 31 which, as previously stated, may beemployed for cracking, catalytic dehydrogenation or. thermalpolymerization. When this vessel is cracking or catalyticdehydrogenation, the eiliuent therefrom passes through line 3B to aseparator 39 from the top of which C2 and lighter hydrocarbons areremoved from the system and from the bottom of which C; to C5hydrocarbons are pumped through line 40 to line 33b.

Line 38 is provided with a valve 4| and with a branch line 42 controlledby a valve 43. When chamber 31 is employed for thermal polymerizal isclosed and valve 43 is opened, and from said chamber passes throughbranch line 42 into separator 44 from which gasoline and heavierhydrocarbons are withdrawn by line 46, and C5 and lighter hydrocarbonspass overhead through line 41 back to line 33.

Line 5 is provided with a valve 48 and a branch line 49 controlled by a'valve 50. When it is desired to remove alkyl sulfates from thecirculating sulfuric is opened, and

acid, 4valve 48 is closed, valve 50 the acid, containing alkyl sulfates,

removed from separator 8, is introduced into a' chamber 5| which may beoperated as a hydrolyzlng zone, in which event a. hydrolyzingagent isintroduced` thereinto through reaction chamber for the production ofethers.

The alcohol or ether, as the case may be, leavesv vessel 5I through line53 in which it is conducted to cooler 54 and thence to storage chamber55. Sulfuric acid, which may contain the water added through line 55,goes to a concentrator 51, in any suitable manner, and then through line58 back to line 5. Line 58 is provided Withan inlet 59 for fresh acid.`-

Tanks 1 1, 23, 32, and 55 are provided respectively lwith outlets 60,6|, 612, and 63 leading to a commonline 64. the, blending of theproducts contained in the various storage tanks in any desiredproportions.

It is apparent that many changes may be made in the above describedapparatus without departing from the scope of the present invention. A

Six runs were made with a three-'foot height of sulfuric acid with across-sectional area of 4.9 sq. in. under a pressure of 600lbs./sq. in.The feed was introduced into the acid through a'jet having an internaldiameter of 0.018". One of the runs was made zit-.266 F. in the gasphase to determine what eect a change of phase would have on the yield.-Since jet employed for which may be heated l .is not as emcient as thatoi.' liquids. the feed inl this 4run was not preheated whereby it wasdispersed as liquid and converted to gas in the reactor. 'I'he data for-these runs may be summarized as follows: n

' Run No.

Feed rate, 1./hr 16 16 15 15 l5 Weightpercent acid 50 60 69 69 69gerperature, Fy 224 215 224 221 v26o ec l Mole percent ethane 0.6 0.60.6 0.8 0.8 0 Mole percent propylene 12.5 12.5 12.5 12.8 .12.8 12 Molepercent propane 56.1 56.1 56.1 53.1 53.1 66. Mole percent isobutylene.3.4 3.4 3.4 3.7 3.7 2. ole percent n-butylenes 7. l 7. l 7. 1 7. 0 7.0 4Mole percent butanes 20.1 20.1 20.1 22.2 22.2 14. Mole percent Cri- 0.20.2 0.2 0.4 0.4 0. Exit gas:

Mole percent ethane an lighter 3.6 1.8 1.8 0.2 Mole percent propylene11.0 6.9' 6.8 7.2 Mole percent propane 55.4 60.6 60.3 68.6 Mole percentisobutylenes. 2.7 0.4 0.8 0 8 0.6 Mole percent nbuty]enes 6.0 4.9 5.03.1 Mole percent butanes 20.8 25.1 25.0 18.3 Mole percent 05+ 0.5 0.30.3 2.0 Yield on prop vlene:

Based on product 12.0 4l 65 54 65 Based on olefin reducton 16. 0 94 9086 75 Yield on total nnsats.:

Based on product 19. 3 31 27 32 Based on'oleiln reduction.. 17.5 52 5048 45.5 Olelin reductions:

Percent reduction of iso 64H5.. 23 91 94 87 75 Percent reduction of n-CiHs.. 1 8 39 34 30 Percent reduction of propylene 51 52 43 Percentreduction of total uns s 17.5 52 50 48 45.5 Product -It will be notedthat with acid the yield was mainly isopropyl alcohol. This .is evidentfrom the. fact that whereas only 45% of the product distilled over at1'71,'80% distilled over at 183. It is also to. be observed that the gasphase experiment gave a yield comparable to that rate and` acidtemperature of phase operation,

obtained with the same feed strength in liquid phase 'at a 224 F. Theproduct of the gas however, was somewhat higher boiling, indicatingThisarrangement facilitates dispersion of gases the presence of higherpolymers.

The products ofthe runs made with acid of higher than 50% concentrationcontained varying amounts of isopropyl ether ranging from about 5% to10%. of isopropyl alcohol in the various products, not taking intoconsideration the isopropyl alcohol recovered from the circulating acid,ranged from about 1% to 3%.

The products from and distilled to 329 F.; 75% of the mixture wasrecovered as overhead. This overhead was hydrogenated in the presence ofnickel at 500 F. under a pressure 'of 1600 lbs/sq. in. A 40% blend ofthehydrogenated product in a 74 octane number straight-run naphtha gave ablending octane number o1' 9 3. A similar blend of the straight-runnaphtha with isooctane indicated the blending octane number of theiso-octane to be 92.5. Thus acid treatment thefhydrogenated 'product ofthe of the C's and C4 cut is about equal to iso-octane as a blendingagent for- Runs 3 and 4 were mixed o! the distillation was a 'l0 aqueoussolution of normalbutylene. The results were as follows: isopropylalcohol. In the run itself 1616 grams ot vliquid product was obtained.1000 'grams o! Run No. isopropyl alcohol was obtained from the spentacid. Thus, the total weight per cent yield o! 47 s product, based onthe propylene, was 65% (shown y in the data above) plus 28.6% (yield ofalcohol) Poiyiiirligldi: 9/9 or 93.6%. This figure checks'with thefigure weigmgmuwmmamm- ...-1 given in theabove table for yield based onPolyvggi gentonisobutylene 191 propylene reduci-dgn- U 1() Percentrdpylenepolymerlzed 58.5 Several analytical d1stlllations were run onPnobut lg lglllyelggg-z-e-m *gli ai products of polymerization ofpropane-butane poymmnspectim: y mixtures. The estimates of thecompositions o! Pfnit WW 82 85 om N6. fsa o.H.As'rM 85.2 s4. the variousproducts are tabulated below with 02mg Nagfngim man polymer 01.4.4 95.the respective feeds to the polymerization unit y 4 for the severalproducts. The product obtained in Run No. 7 over a reac- Sample No.

1 2 n ya 4 :il

Temp..I- 22's 225 224 221 200 Weight percent acid 69 69 69 69 66 gentilheight, reet a a a a 3 M01@ percent 10.11. 3.1 5.4 3.4 3.7 2.2 Molepercent n-CHs... l. 7. 9 0. 7 7. 1 7. 0 4. l Mole percent CiHq 8.6 7. 5l2. 5 l2. 8 l2. 1 Total 19.0 ne 23.0, am 18.4 Ram: iso-orHB/n-oHS/om1/2. sla s 1/1. 911.4 i/a 1/a.1 1/1. 0/3. s 1/1. sels. 5 Percentreacted:

s1 87 01 04 ...-15 :nas ai -so 4a 4c 51 se 4s .11. 42/1 107/1 ae/i aan4.4/1 1.42 1.es/1/1.01 1.15/1/1131 1an/as 1.a2/1/t4 is Cass/0m1- oiefins12. aa 111.21 1/2. 0 1/1. s 1 4. 1 Percent reduction of unsats... 4646.5 A 52 50 45.5 Estimates of product:

Percent isopropyl ether 8 l 5 10 10 Percent C+C1 hydrocarbons 14 y'14 lll5 Percent C; hydrocarbons 62 52 38l 25 Percent C|Cu+hydrocarbons 13 2338 46 Percent loss i 3- 6 3 4 100.0 100.0 100.0 100.0

The per cent isopropyl ether in the product Y tion period of 132 hourshad the following averapparently increases with increasing feed ratioage characteristics; f of CaHe to 04H8. Samples 5 and 3 contain a-considerably higher percentage of material above Product! 1 Sample Smal60% 243 e. e 70% 1 v.253

90% 350 F. B. aas 34s 95% 359 Percent recovery 88.0 87.0 F. B P. o F 361.5 Comparative results. obtained by processing a 'gg' 9L;

feed containing propylene and butylenes and one Anmne point o F 103containing only butylenes respectively. were obtained by treating therespective feeds in a, re-

Ananalytical distillation of this product showed actionchamber having an1l it. height of 60% 6 5 that, on the average, it contained about 2% ofsulfuric acid with a crosslsectional area of 9.6 sopropyi ether. A cutof this product obtained sq. in. The operating temperature was 225 F.,by distlling the product to 911.85% overhead the pressure was 425lbs/sq. in. and the feed yielded, upon hydrogenati'on, a product havingrate was 24 liters/hour. The feed was introan octane number of 95.6. Theunhydrogenated duced.l into the reaction chamber through a jet productusually contains about 9 and 10 mole having aninternal diameter of0.023". per cent reacted propylene in the form of ether, In Run'No. 7thefeed contained 4.9% propylalcohol, and the unsaturated hydrocarbons06H12. ene, 1'7.l'%isobutylenc, and 26.5% of normal C1H14, and Cel-11e,and higher hydrocarbons. The butyiene. In Run fNo. 8 the feed containedno first traction fromthe distillation of this product propylene,7.2%"of .isobutylene, and 18.4% o! im? an ethereal odor. The presence ofhexylene v hydrocarbon in this first overhead was indicated by itsrefractive index and boiling point.

'I'he following example illustrates advantages of operation according tothe preferred method of this invention. A crude polymer, obtained byco-polymerization of C: and C4 olens and con-'- taining isopropyl ether,was found to have an octane number of 85.6. Hydrogenation of thispolymer product to saturate the double bonds produces a saturatedproduct having an octane number of 90.0. But when th'e isopropyl etheris separated before the hydrogenation, the rea fraction containingisopropyl ether and a hymaining polymer being hydrogenated under thesame conditions as before, and the isopropyl ether is then reblendedwith the hydrogenated polymer, the inal blend has an octane number of93.3'. 'In addition to this increased octane number'the yield isalsogreater'in the second case as hydrogenation of isopropyll ether to pro-Dane is avoided.

The experiments described above do not, of course, define the metes andbounds of the present invention. They are complete operations carriadout under various conditions falling ,within the broad ranges ofoperating conditions heretofore described and esta lished by experimentsof a qualitative nature.

It is tobe understood that' while it is preferred to employ, tis a'feedstock in the process of the present invention, one containing propyleneand both isoand normal butylene, this process may be practicedsuccessfully on any feed stock containing propylene and any olefincontaining 4 or 5 carbon atoms.

The nature and objects of the present invention having beenthusdescribed and illustrated, what is claimed as new and useful,and'desired to be secured by Letters Patent is:

1. A process for the production of a motor fuel of high octane numberwhich comprises contacting a mixture the olefin content essentiallycomprising propylene and at least one other olein of higher molecularweight and having no hydrocarbon constituents containing more than 5carbon atoms with sulfuricsacid of'a concentration between 55% and 7,5%at a temperature between 175 and 300 F. and under elevated pressure,separating a reaction product predominantly boiling within the gasolinerange and cong a minor amount of isopropyl ether from the sulfuric acid,dividing the reaction product into a fraction containing isopropyl etherand a fraction boiling in the motor fuel range, then saturating thedouble bonds in the said hydrocarbon .fraction with hydrogen.

y ing the hydrogenated containing isopropyl ether.'

containing less than 6 carbon atoms with sulfuric acid under conditionscausing vthe formation of a polymerization reaction productpredominantly containing hydrocarbon polymers boiling in the motor fuelrange and a minor amount of isopropyl ether, removing the reactionproduct from the sulfuric acid, dividing the reaction product intodrocarbon fraction, saturating the double bonds in the said hydrocarbonfraction with hydrogen, and combining the hydrogenated product with thefraction containing isopropyl ether.

3. A process for the production of a motor fuel of high octane numbercontaining isopropyl ether .which comprises contacting a mixture theolefin content essentially comprisingvpropylene and at least one otherolefin `of higher molecular weight and having no hydrocarbonconstituents containing .more than 5 carbon atoms with sulfuric acid ofa concentration between 55% and 75% at a temperature between-175 and 300F. and under elevated pressure, removing the `reaction product andlunconverted initial material from the sulfuric acid, separating thereaction product from the unconverted initial material, dividing thereaction product into a fraction containing isopropyl ether and a higherboiling hydrocarbon fraction, said`latter fraction constituting themajor portion of the reaction product, saturating the double bonds inthe said higher boiling hydrocarbon fraction with hydrogen, andcombinproduct with the fraction 4. A process according to claim 3 inwhich the feedstock is a mixture containing C3 and C4 olefins. s

5. A process according to claim 3 in which the said mixture is passedthrough a body of sulfuric f acid at a rate varying between about 11/2and '7 propyl ether, and

-2. A process for the production of a motor fuel reaction product.

liters/hr./ft. of acid height of a cross-sectional area of about 0.05sq. ft.

6. In the process for the production of motor fuel of high octane numberby contacting a hydrocarbon mixture, the olefin content of whichessentially comprises propylene and atleast one olefin of highermolecular weight containing less than six carbon atoms'per molecule,with sulfuric acid under conditions causing the formation of apolymerization reaction product predominantly containing hydrocarbonpolymers boiling in the motor fuel range and a ininor amount ofisoremoving the reaction product, from the sulfuric acid mixture, theimproved steps comprising separating afraction containing .substantiallyall of the isopropyl ether from the and hydrogenating at least areaction product portion of the substantially isopropyl-ether-fx'eeELDoN E. s'rAHLY.

